1. Field of the Invention
The present invention relates to an electronic component module in which an electronic component mounted on a substrate is sealed by a resin sealing portion.
2. Description of the Related Art
There has been known an electronic component module in which an electronic component is provided on a substrate and sealed by providing a resin sealing portion on the substrate with the electronic component mounted.
For example, Japanese Unexamined Patent Application Publication No. 2005-302835 discloses a semiconductor device configured such that a solder joint portion provided between an electronic component a semiconductor element or a passive component) and a substrate is surrounded by a hollow portion to restrict solder flashing that occurs during reflowing, a resin film is bonded in a close contact manner on the entire surface of the substrate with the electronic component mounted and is hardened to form a film-shaped resin layer to improve sealing properties of the hollow portion and the electronic component, and then liquid resin is applied to cover the film-shaped resin layer and is hardened to form an embedding resin layer. Hence, the electronic component on the substrate is covered with a resin sealing portion having a two-layer structure including the film-shaped resin layer and the embedding resin layer.
Also, Japanese Unexamined Patent Application Publication No. 2006-245989 discloses a surface acoustic wave device including a resin sealing portion having a three-layer structure so that a surface acoustic wave element serving as an electronic component on a substrate is sealed. The surface acoustic wave device disclosed in Japanese Unexamined Patent Application Publication No. 2006-245989 is configured such that two layers included in the resin sealing portion having the three-layer structure located at a side near the surface acoustic wave element are formed of film-shaped resin layers, and the residual one layer is formed of an embedding resin layer, to improve the thermal shock resistance. Further, the physical properties, such as elastic coefficients and coefficients of linear expansion, of the film-shaped resin layers and the embedding resin layer satisfy predetermined conditions.
However, typically for this kind of electronic component module, it is not sufficient if only one of the sealing properties and the thermal shock resistance is satisfied, and it is important to ensure both the sealing properties and the thermal shock resistance.
To improve the sealing properties, to cause the resin film to be the above-described film-shaped resin layer to closely contact the electronic component and the substrate, the resin film may be preferably formed of a relatively soft member having high extensibility. However, in this case, the elastic coefficient of the resin film may generally become low. It may be difficult to obtain sufficient joining reliability in view of thermal shock resistance.